"We took an extraordinary step to put officers on 12-hour tours this holiday weekend," said McCarthy, speaking at the 11th District Police Station, 3151 W. Harrison St. The change resulted in a 30-percent increase in police presence, he said.

McCarthy displayed an array of firearms on a table at the press conference, saying that Chicago Police seized "about one illegal gun per hour" over Fourth of July weekend thus far.

"I expect that number will increase as we tally our official figures," he added. McCarthy continued to advocate for stricter gun laws, which has been his rallying cry for almost his entire stint as top Chicago Police officer.

Amari was shot, along with a 26-year-old woman, just before midnight. Sunday morning, police said they were not the intended targets of the shooting; McCarthy confirmed that police believe the target was Amari's father, who he said is a "ranking gang member" with 45 previous arrests, including for illegal gun possession.

McCarthy said he was most recently arrested on a gun charge in April, but then released the next day. "If Mr. Brown is in custody," McCarthy said, "his son is alive. That's not the case. Quite frankly, he shouldn't have been on the street.

"It's real simple," he continued. "Gun possessors are potential murderers. If they don't learn a lesson for carrying the gun, they keep carrying the gun. They get into an argument, now instead of fighting, they shoot."

McCarthy said there need to be stricter gun laws and blamed "the gun lobby" for the lack of political motivation to pass them.

McCarthy said that Amari's father is not cooperating with the investigation, but other neighbors are: "Even in our most distressed, difficult communities, there's people, good people who are helping us."

He credited the increased police presence for the arrest related to the Streeterville shooting Saturday night in which a man was injured just about an hour after the nearby Navy Pier fireworks show. "[The shooting] took place right in front of one of our uniformed police officers. Our officers were in the right place at the right time. They pursued the individual, recovered the weapon and arrested the offender," he said.